The Boot-Strap Method and the least-squares ambiguity decorrelation adjustment (LAMBDA) method are two different methods for estimating double difference carrier phase integer ambiguity using a carrier phase from two GPS receivers. The boot-strap method provides integers for the double difference carrier phase and also provides an analytical solution for a probability that the integers found are incorrect (i.e., not all integers are correct), for example, a probability that the boot-strap method has failed Pboot-fail. However, since the boot-strap method does not use residual errors, it has no capability for rejecting anomalous data.
The lambda method provides integers for the double difference carrier phase which may be different from those found by the boot-strap method. In addition, the lambda method allows rejection of anomalous data through a built-in analysis of residual errors, and by a comparison of best and second-best residual ratio (“the ratio test”). However, there is no known practical, analytical solution for a probability of failure for the lambda method, Pλ-fail.